1. Technical Field
Various embodiments relate to a memory device and a system including the same, and more particularly, to a technology capable of reducing a refresh current of a memory device.
2. Related Art
Recently, mobile electronic devices including smart phones require large-capacity DRAM. In general, data stored in a memory cell of a semiconductor memory device such as DRAM may be changed by a leakage current. Thus, a refresh operation is required to periodically recharge the memory cell having the data stored therein.
That is, a memory cell of a dynamic semiconductor memory such as DRAM stores data on a capacitive element. Due to a charge leakage from the capacitive element, the memory cell must be periodically refreshed. The refresh process typically includes a step of performing a read operation to get a charge level in the original state, the charge level being stored in the memory cell.
As time elapses, different types of refresh methods have developed. According to an auto refresh method which is one of the refresh methods, a refresh timer exist outside a memory chip, and the memory chip performs a refresh operation in response to a periodic refresh command supplied by a controller.
According to a self-refresh method which is another of the refresh methods, a refresh timer exists in a memory chip, and all memory chips request a refresh start command from a controller.